Stable ethanol synthesis via dimethyl oxalate hydrogenation over the bifunctional rhenium-copper nanostructures: Influence of support

Abstract

Addition of oxophilc rhenium to decorate small copper nanoparticles has been validated to be an efficient method to prepare a low-copper catalyst for the direct synthesis of ethanol via dimethyl oxalate (DMO) hydrogenation process, and herein we investigated the impact of supports on the catalytic performance of ReCu catalysts. A series of materials including activated carbon (AC), Al2O3, SiO2, TiO2 and ZrO2 were utilized as the support and as prepared Re2Cu5 catalysts were evaluated. The results exhibited that the Re2Cu5/ZrO2 catalyst possesses the highest DMO hydrogenation activity and ethanol yield (∼93%), which may be due to its lowest Cu0/Cu+ ratio (0.13), smallest Cu particle size (∼0.84 nm) a relative high reduction degree (59%). The CO adsorption behavior characterized by in situ IR spectroscopy showed that a strong metal-support interaction creates an electron deficient environment of Cu nanoparticle, resulting in a lower Cu0/Cu+ ratio that enhances the activation of CO bond in the DMO molecular.